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Cecil Moore wrote:
I've described it before. I used a dual-trace 100 MHz O-scope and estimated the phase angle between the two traces at about 7% of a cycle. That phase angle was certainly NOT ANYWHERE NEAR the 4.5 degrees reported by W8JI. W8JI measured a 4.5 degree phase shift in the standing-wave current being used for the measurement although virtually no phase information exists in the standing-wave current phase. W7EL made exactly the same mistake in his measurements. No wonder the two agree. *Chuckle* I made the "mistake" of measuring current, the definition of which can be found in any elementary electrical circuits text. Contrary to Cecil's objections, phase is a property of periodic steady state current (as can also be discovered from reading a basic text), and certainly can be measured. I measured it and so did Tom, but Cecil sure doesn't seem to like the results. Cecil's and his scope are apparently able to measure something else -- whatever it is, I'm afraid my scope doesn't have the magical properties needed to measure it. I did, however, do at least a couple of things which Cecil might have overlooked. One is that I was careful to terminate each of the current probes with a low-resistance low-reactance load to reduce the insertion impedance to a very low value. Another is that I put both probes on the same wire to verify that their outputs were in phase. These steps alone might have broken the magic spell necessary to measure whatever different kinds of current Cecil imagines. Can anyone point me to any reference to "standing-wave current" in any reputable text? As far as I can tell, it's something Cecil made up to mean whatever is necessary at the moment to discount others' measurements. It seems to be working quite well -- in the endless discussions, he's trotted it out many times without anyone to my recollection even asking him what it is and how it differs from the current described in textbooks (you know, the rate of charge flow?). Or why "virtually no phase information" exists in it. A periodic waveform with no phase information? Huh? There's no mystery about traveling or standing waves -- both are very well understood, mathematically rigorous, and have been used for over a century with great success in the design of countless real things that work. But muddled "standing wave currents" and bouncing waves of average power, supported only by hand waving and misdirection, don't bear much resemblance to the highly developed, rigorous, and self-consistent body of knowledge that's served us so well for so long. But each to his own. Roy Lewallen, W7EL |
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